As used in this specification the term `oat groats` means dehulled oat grains or hull-less oat grains, where oat is defined as referring to all members of the genus Avena.
Traditionally, oat is not the subject of detailed fractionation into discreet components or fractions of specific composition of matter. Current commercial practice is limited to dry milling and screening of either enzyme-inactivated oat groats or oat flake (rolled oats) to give a coarse fraction known as `oat bran` and a finer fraction known as `oat flour`. Several process prototypes describe ways of obtaining purer brans and flours. Hohner and Hyldon in U.S. Pat. No. 4,028,468, 1977, describe a process which first involves hammer milling of the oat groat prior to any wet fractionation taking place. A drawback of this approach lies in the fact that any random dry comminution produces a spectrum of particle sizes which places constraints on downstream separation or screening equipment. Myllymaki et al., in U.S. Pat. No. 5,312,636, 1994, employed a roller mill followed by screening to obtain a crude oat bran which then must be refluxed in 80% isopropyl alcohol to inactivate the lipase known to be present in this fraction. Lehtomaki et al. in U.S. Pat. No. 5,183,677 1993) described a process in which oats were rapidly ground in cold water &lt;8.degree. C., homogenized and screened to give a bran product stated to contain beta-glucan in the range 15-40% by weight. Few operating details were recited in this disclosure to allow anyone skilled in the art to practice the invention. No mention was made of the nature or composition of the remaining material not recovered in this process. Burrows et al., in Canadian Patent 1,179,189, 1984 described a process which took advantage of the selective activity of endosperm cell wall degrading enzymes to effectively fractionate the bran from the flour but the products were unstable due to rancidity. Collins and Paton, in U.S. Pat. No. 5,169,660, 1992 made improvements to the Burrows et al. technology by employing 80% aqueous alcohol as the wet milling medium following a steeping period, which produces stable products without the need for refluxing. Although separation efficiencies have been demonstrated in these processes, the total process time can be in excess of 30 h which is considered too lengthy for full commercial implementation.
Oat has long been known to contain a gummy substance commonly referred to as beta-glucan. This non-starch polysaccharide is composed of glucose units joined together in contiguous runs of beta 1,3 and beta 1,4 linkages. Although there has been an interest in this substance for both food and non-food uses for many years (Hohner & Hyldon, U.S. Pat. No. 4,028,468; Goering et al. U.S. Pat. No. 4,804,545; Lehtomaki et al. U.S. Pat. No. 5,106,640 and U.S. Pat. No. 5,183,677; Myllymaki et al. U.S. Pat. No. 5,312,636; Bhatty U.S. Pat. No. 5,518,710), a satisfactory process to isolate and prepare the polysaccharide in high purity and in a functionally useful form has not yet been developed. Most attempts to prepare oat beta-glucan have involved using either ground oat flake or a sifted fraction therefrom commonly referred to as oat bran. It has also been recognized that oats contain an enzyme, beta-glucanase, which unless inactivated, will rapidly de-polymerize the beta-glucan in aqueous solution/dispersion. Current methods of inactivation commonly employ a combination of heat, moisture and time.
Current attempts to prepare oat beta-glucan at the commercial level are less than successful from several standpoints. Firstly, oat groats nominally contain 3-5% beta-glucan which is not sufficiently high to be economically attractive. Also, in the course of enzyme inactivation, some of the oat starch may be structurally altered and the protein denatured which renders a total recovery of oat components in a functional form somewhat deficient. Current approaches also make use of repeated or sequential treatments involving alkaline extraction and acid neutralization. This can result in a high residual protein content in the final product, product discolouration and lower functional viscosity.
In U.S. Pat. No. 5,169,660, Collins and Paton describe the steeping of whole oat groats and their subsequent wet milling and screening in aqueous alcohol, which yields a bran depleted in flour but enriched in beta-glucan gum, and a flour that is depleted in bran but enriched in starch and protein. In order to loosen the sub-aleurone bran layers from the inner endosperm, the groats must be steeped in water for up to 24 h with total processing time around 30 h. The long processing time translates into increased equipment and labour costs and limits the volume of oats that may be processed per unit time. Further, our prior invention requires a working concentration of 80% w/w of an aliphatic alcohol which further makes the process costly to operate.
Exposure of skin to chemicals contained in topical cosmetic and pharmaceutical compositions can result in adverse reactions, including irritation response and contact sensitization of the skin. As used herein, the term cosmetic and pharmaceutical composition is used in the widest sense and encompasses any composition that is applied to the skin for a beneficial effect. As used herein, contact sensitization of the skin refers to adverse systemic immunological reactions of the skin, e.g. itching, burning, swelling or redness. Irritation response of the skin involves similar symptoms in which the systemic immune system plays no role.
A small but significant segment of the population is particularly prone to such irritation response and contact sensitization of the skin. As a consequence, the use of a wide variety of topical preparations for the skin by this segment of the population is at best, an unpleasant task. For example, compositions containing paraminobenzoic acid (sunscreens) or Balsam of Peru are known to cause contact sensitization, and certain chemicals, e.g. vasodilators and surfactants are known to cause irritation response when used by some people.
In addition, certain types of physical contact with human skin can cause irritation. For example, the removal of hair from human skin by waxing methods is known to cause some degree of irritation to most, if not all, persons. Hereinafter, the types of physical contact that cause irritation response of human skin are referred to as `contact physical irritants`.
Anti-irritants can be derived from mineral and botanical sources. For example, extracts of seeds of Cola nitida (Vent.)A.Chev. can be added to cosmetics to achieve an anti-irritant effect (U.S. Pat. No. 5,028,428). Furthermore, salts of strontium are also capable of suppression of irritation response to contact physical irritants (U.S. Pat. No. 5,716,625). Oat groats are known to contain anti-irritants but no commercial method or patent has led to a means to concentrate such an anti-irritant. A preferred embodiment of the present application describes the extraction of a dry powdered anti-irritant or a dissolved form oat based anti-irritant that exceeds the activity of Cola nitida (Vent.)A.Chev. extracts.
In industry, lipase enzymes originate mostly from microbial sources and pancreatic extracts, and are used widely for hydrolysis of fats and oils. Recently industrial lipases have been identified that hydrolyze specific fatty acids. Other industrial lipases are used to form triglycerides and esters from free fatty acids and the appropriate alcohol.
Lipase preparations can be obtained from various grains and seeds (Hassanien et al. 1986. J. Am. Oil Chem. Soc., 63:893-897). Oat seeds are particularly rich in lipase. Hammond and Lee (U.S. Pat. No. 5,089,403) demonstrated that oat groats could be used to hydrolyse triglycerides. Piazza and coworkers (Piazza et al. 1989. Biotechnology Letters Vol. 11 No. 7 487-492) demonstrated that oat lipase specifically cleaved unsaturated fatty acids from tallow triglycerides when in an aqueous solution. However, in nonpolar solutions, little specificity of oat lipase prepared from whole ground oat groats was found in the hydrolysis of soybean, corn and olive oil (Piazza 1991. Biotechnology Letters Vol. 13 No. 3 173-178) and castor oil (Piazza 1991. Biotechnology Letters Vol. 13 No. 3 179-184). In Piazza's methods, 0.4 g of oil was hydrolyzed in 24-48 h using 4 g of ground groats. Although the specificity of the lipase is useful for industrial processes, oat lipase from ground groats is not sufficiently active for most industrial applications.
One preferred embodiment of the present invention describes the means to prepare an oat lipase product on solid support that has lipase activity similar to that observed for commercial enzyme preparations.
It has long been known that oat groats are relatively rich in oil when compared with other grass seeds. However, all oat oil fractions are difficult to extract and refine. Present processing techniques allow the extraction of oat oil from whole oat groats. Boczewski extracted oat oil from oat groats by admixing rolled dehulled oats with a nonpolar solvent (U.S. Pat. No. 4,220,287). Potter et al. (U.S. Pat. No. 5,620,692) describe the recovery of oil from cereal grains using hexanes or heptanes as extraction solvents. The solvent is then eliminated by evaporation, typically distillation. The resulting crude vegetable oil contains numerous fine particles consisting predominantly of proteins (20-60%). The crude oil is then subjected to various refining steps including filtration to remove particulates, water washing to remove solids and gums, acid washing to remove phosphatides, alkali neutralization to remove free fatty acids, chilling (`winterization`) to remove high-melting triglycerides, decolourizing (`bleaching`) with activated bleaching earth or activated carbon and deodorizing by heating under vacuum. Potter et al. claimed that oil prepared in this manner left a greasy feel on the skin and was not readily absorbed. The preferred embodiment of U.S. Pat. No. 5,620,692 to prepare oat oil involved first hexane extraction of whole oat flour followed by removal of the solvent phase. The remaining oil was heated in a jacketed tank to 70-75.degree. C. and 3% weight of soft water was added to the oil. The oil and water were stirred for 30 minutes and then centrifuged to remove solid material. The water washing was repeated to yield a clarified oil. The oil was then dried under nitrogen at 100-105.degree. C. The oil was finally degummed by the addition of either phosphoric or citric acid.
Oat oil has higher levels of phospholipid and free fatty acids than other oils and is difficult to refine as described above. Refining oat oil to remove fatty acids and phospholipids results in considerable product losses. We disclose methods whereby oat oil quality is improved by drying the pearlings to less than 4% moisture. Removal of water allows the endogenous oat lipase catalyst to reduce the free fatty acid level in the pearlings. This step alone greatly reduces refining losses. We also disclose that surprisingly, extraction of the pearlings with aqueous ethanol selectively removes colour impurities and phospholipids. Oat oil extracted from pearlings that have been previously extracted with aqueous ethanol, is light in colour, low in phopholipids and easily refined to a commercial product with acceptable losses.